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Pascale F, Gueddida S, Doll K, Dovesi R. Band gap, Jahn-Teller deformation, octahedra rotation in transition metal perovskites LaTiO 3 . J Comput Chem 2024; 45:683-694. [PMID: 38095335 DOI: 10.1002/jcc.27274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 11/15/2023] [Accepted: 11/17/2023] [Indexed: 03/02/2024]
Abstract
The LaTiO3 perovskite (where Ti is in a d1 state) is investigated by using an all electron Gaussian basis and many functionals, ranging from pure GGA (PBE), to hybrids (full range, B3LYP and PBE0, and range separated, HSE06) to Hartree Fock. Recently, Varignon et al. (Phys. Rev. Res 1, 033131, 2019), showed that, when GGA+U or HSE06 are used, a metallic solution and fractional occupancy of the t2 g subshell are obtained. Here, it is shown that when a full range hybrid functional is used, an integer occupancy is obtained, as suggested by the Jahn-Teller theorem. When the exact exchange percentage varies from 0 to 100, the system is insulating when it exceeds 20. By reducing progressively the symmetry from cubic down to orthorhombic, the relative importance of the Jahn-Teller deformation and of the rotation of the octahedra is explored.
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Affiliation(s)
- F Pascale
- Université de Lorraine-Nancy, CNRS, LEMTA, Nancy, France
| | - S Gueddida
- Université de Lorraine-Nancy, CNRS, LPCT, UMR, Vandoeuvre-lés-Nancy, France
| | - K Doll
- University of Stuttgart, Molpro Quantum Chemistry Software, Institute of Theoretical Chemistry, Stuttgart, Germany
| | - R Dovesi
- Accademia Delle Science di Torino, Torinoto, Italy
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Berro Y, Gueddida S, Bouizi Y, Bellouard C, Bendeif EE, Gansmuller A, Celzard A, Fierro V, Ihiawakrim D, Ersen O, Kassir M, El Haj Hassan F, Lebegue S, Badawi M, Canilho N, Pasc A. Imprinting isolated single iron atoms onto mesoporous silica by templating with metallosurfactants. J Colloid Interface Sci 2020; 573:193-203. [PMID: 32278950 DOI: 10.1016/j.jcis.2020.03.095] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 03/12/2020] [Accepted: 03/26/2020] [Indexed: 01/03/2023]
Abstract
HYPOTHESIS One of the main drawbacks of metal-supported materials, traditionally prepared by the impregnation of metal salts onto pre-synthesized porous supports, is the formation of large and unevenly dispersed particles. Generally, the larger are the particles, the lower is the number of catalytic sites. Maximum atom exposure can be reached within single-atom materials, which appear therefore as the next generation of porous catalysts. EXPERIMENTS Herein, we designed single iron atom-supported silica materials through sol-gel hydrothermal treatment using mixtures of a non-ionic surfactant (Pluronic P123) and a metallosurfactant (cetyltrimethylammoniumtrichloromonobromoferrate, CTAF) as porogens. The ratio between the Pluronic P123 and the CTAF enables to control the silica structural and textural properties. More importantly, CTAF acts as an iron source, which amount could be simply tuned by varying the non-ionic/metallo surfactants molar ratio. FINDINGS The fine distribution of iron atoms onto the silica mesopores results from the iron distribution within the mixed micelles, which serve as templates for the polymerization of the silica matrix. Several characterization methods were used to determine the structural and textural properties of the silica material (XRD, N2 sorption isotherms and TEM) and the homogeneous distribution and lack of clustering of iron atoms in the resulting materials (elemental analysis, magnetic measurements, pair distribution function (PDF), MAS-NMR and TEM mapping). The oxidation and spin state of single-iron atoms determined from their magnetic properties were confirmed by DFT calculations. This strategy might find straightforward applications in preparing versatile single atom catalysts, with improved efficiency compared to nanosized ones.
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Affiliation(s)
- Y Berro
- L2CM UMR CNRS 7053, Université de Lorraine, 54506 Vandœuvre-lès-Nancy, France; LPCT UMR CNRS 7019, Université de Lorraine, 54506 Vandœuvre-lès-Nancy, France; PRASE, Université Libanaise, Hadath, Lebanon
| | - S Gueddida
- LPCT UMR CNRS 7019, Université de Lorraine, 54506 Vandœuvre-lès-Nancy, France
| | - Y Bouizi
- L2CM UMR CNRS 7053, Université de Lorraine, 54506 Vandœuvre-lès-Nancy, France
| | - C Bellouard
- IJL UMR CNRS 7198, Université de Lorraine, 54000 Nancy, France.
| | - El-E Bendeif
- CRM2 UMR CNRS 7036, Université de Lorraine, 54506 Vandœuvre-lès-Nancy, France
| | - A Gansmuller
- CRM2 UMR CNRS 7036, Université de Lorraine, 54506 Vandœuvre-lès-Nancy, France
| | - A Celzard
- IJL UMR CNRS 7198, Université de Lorraine, 88000 Epinal, France
| | - V Fierro
- IJL UMR CNRS 7198, Université de Lorraine, 88000 Epinal, France
| | - D Ihiawakrim
- IPCMS UMR CNRS 7504, Université de Strasbourg, 67034 Strasbourg, France
| | - O Ersen
- IPCMS UMR CNRS 7504, Université de Strasbourg, 67034 Strasbourg, France
| | - M Kassir
- PRASE, Université Libanaise, Hadath, Lebanon
| | | | - S Lebegue
- LPCT UMR CNRS 7019, Université de Lorraine, 54506 Vandœuvre-lès-Nancy, France
| | - M Badawi
- LPCT UMR CNRS 7019, Université de Lorraine, 54506 Vandœuvre-lès-Nancy, France
| | - N Canilho
- L2CM UMR CNRS 7053, Université de Lorraine, 54506 Vandœuvre-lès-Nancy, France
| | - A Pasc
- L2CM UMR CNRS 7053, Université de Lorraine, 54506 Vandœuvre-lès-Nancy, France.
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